Design On Sensorless Control System For Brushless DC Motor

The advancement of electronics technology, motor technology and microcontroller technology accelerate the development of the eletro-mechanical industry. Since the brush abrasion and arc-shaped mechanism for phase exchange are avoid, the system with brush DC motor that commonly used. The application of power electronics devices greatly reduces the volume of control system. So this kind of control structure is used extensively in industry and civilian projects and with a wonderful view in the field of servo system.In this chapter, the method of BLDCM rotor position detection is first discussed. Then the principle and algorithm of Bemf zero crossing point detection is explained. In succession, the chapter dissertates the software realization of the Bemf zero crossing point detection algorithm, the software disturbance filter and the modification of phase displacement, and the software realization of commutation point. Finally, the chapter, dissertates the strategy of software open-loop commutation start-up. The hardware and software design of the digital control system is dissertated in detail. The chapter of hardware design first expounds the whole design. Then the design of several primary circuits is discussed and the choice of some important electronic components and their parameters in these circuits is analysed emphatically. The chapter of software design also first expounds the whole design. Then some problems on software realization are dissertated. Next a few primary sub routines are expatiated. At last, the whole control strategy of the digital system is presented.The experimental results indicate that the control system of DSP can make the motor start fast and stable with wider area of speeding. This BLDCM control system has the characteristics of simple structure, high dependability, and can be used in many fields.